Given the inequality:
$$x \sin{\left(\frac{7}{15} \right)} \geq \frac{\sqrt{3}}{2}$$
To solve this inequality, we must first solve the corresponding equation:
$$x \sin{\left(\frac{7}{15} \right)} = \frac{\sqrt{3}}{2}$$
Solve:
Given the linear equation:
sin(7/15)*x = sqrt(3)/2
Expand brackets in the left part
sin7/15x = sqrt(3)/2
Expand brackets in the right part
sin7/15x = sqrt3/2
Divide both parts of the equation by sin(7/15)
x = sqrt(3)/2 / (sin(7/15))
$$x_{1} = \frac{\sqrt{3}}{2 \sin{\left(\frac{7}{15} \right)}}$$
$$x_{1} = \frac{\sqrt{3}}{2 \sin{\left(\frac{7}{15} \right)}}$$
This roots
$$x_{1} = \frac{\sqrt{3}}{2 \sin{\left(\frac{7}{15} \right)}}$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} \leq x_{1}$$
For example, let's take the point
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$- \frac{1}{10} + \frac{\sqrt{3}}{2 \sin{\left(\frac{7}{15} \right)}}$$
=
$$- \frac{1}{10} + \frac{\sqrt{3}}{2 \sin{\left(\frac{7}{15} \right)}}$$
substitute to the expression
$$x \sin{\left(\frac{7}{15} \right)} \geq \frac{\sqrt{3}}{2}$$
$$\left(- \frac{1}{10} + \frac{\sqrt{3}}{2 \sin{\left(\frac{7}{15} \right)}}\right) \sin{\left(\frac{7}{15} \right)} \geq \frac{\sqrt{3}}{2}$$
/ ___ \ ___
| 1 \/ 3 | \/ 3
|- -- + -----------|*sin(7/15) >= -----
\ 10 2*sin(7/15)/ 2
but
/ ___ \ ___
| 1 \/ 3 | \/ 3
|- -- + -----------|*sin(7/15) < -----
\ 10 2*sin(7/15)/ 2
Then
$$x \leq \frac{\sqrt{3}}{2 \sin{\left(\frac{7}{15} \right)}}$$
no execute
the solution of our inequality is:
$$x \geq \frac{\sqrt{3}}{2 \sin{\left(\frac{7}{15} \right)}}$$
_____
/
-------•-------
x_1